The present invention relates generally to the field of underground boring and, more particularly, to an excavation system which employs a navigation sensor system and an adjustable steering mechanism provided on or in a down-hole cutting tool.
Utility lines for water, electricity, gas, telephone and cable television are often run underground for reasons of safety and aesthetics. In many situations, the underground utilities can be buried in a trench which is then back-filled. Although useful in areas of new construction, the burial of utilities in a trench has certain disadvantages. In areas supporting existing construction, a trench can cause serious disturbance to structures or roadways. Further, there is a high probability that digging a trench may damage previously buried utilities, and that structures or roadways disturbed by digging the trench are rarely restored to their original condition. Also, an open trench poses a danger of injury to workers and passersby.
The general technique of boring a horizontal underground hole has recently been developed in order to overcome the disadvantages described above, as well as others unaddressed when employing conventional trenching techniques. In accordance with such a general horizontal boring technique, also known as microtunnelling, horizontal directional drilling (HDD) or trenchless underground boring, a boring system is situated on the ground surface and drills a hole into the ground at an oblique angle with respect to the ground surface. Drilling fluid is typically flowed through the drill string, over the boring tool, and back up the borehole in order to remove cuttings and dirt. After the boring tool reaches a desired depth, the tool is then directed along a substantially horizontal path to create a horizontal borehole. After the desired length of borehole has been obtained, the tool is then directed upwards to break through to the surface. A reamer is then attached to the drill string which is pulled back through the borehole, thus reaming out the borehole to a larger diameter. It is common to attach a utility line or other conduit to the reaming tool so that it is dragged through the borehole along with the reamer.
In order to provide for the location of a boring tool while underground, a conventional approach involves the incorporation of an active sonde disposed within the boring tool, typically in the form of a magnetic field generating apparatus that generates a magnetic field. A receiver is typically placed above the ground surface to detect the presence of the magnetic field emanating from the boring tool. The receiver is typically incorporated into a hand-held scanning apparatus, not unlike a metal detector, which is often referred to as a locator. The boring tool is typically advanced by a single drill rod length after which boring activity is temporarily halted. An operator then scans an area above the boring tool with the locator in an attempt to detect the magnetic field produced by the active sonde situated within the boring tool. The boring operation remains halted for a period of time during which the boring tool data is obtained and evaluated. The operator carrying the locator typically provides the operator of the boring machine with verbal instructions in order to maintain the boring tool on the intended course.
It can be appreciated that present methods of detecting and controlling boring tool movement along a desired underground path is cumbersome, fraught with inaccuracies, and require repeated halting of boring operations. Moreover, the inherent delay resulting from verbal communication of course change instructions between the operator of the locator and the boring machine operator may compromise tunneling accuracies and safety of the tunneling effort. By way of example, it is often difficult to detect the presence of buried objects and utilities before and during tunneling operations. In general, conventional boring systems are unable to quickly respond to needed boring tool direction changes and productivity adjustments, which are often needed when a buried obstruction is detected or changing soil conditions are encountered.
Another conventional approach to detecting the location of a drill bit used in vertical oil or gas well drilling applications involves the use of a down-hole gyroscope-based surveying tool. Examples of such an approach are disclosed in U.S. Pat. Nos. 5,652,617; 5,394,950; 4,987,684; 4,909,336; 4,739,841; 4,454,756; 4,302,886; 4,297,790; 4,071,959; 4,021,774; and 3,845,569; all of which are hereby incorporated herein by reference in their respective entireties. These and other conventional approaches are specifically designed for use in vertically oriented wells (e.g., along a relatively fixed vertical axis).
Moreover, such conventional down-hole gyroscope-based surveying tools are generally used to facilitate maintaining of drill bit progress in the vertical direction. Also, many of the systems disclosed in the above-listed patents are employed to survey a previously excavated vertical well. Further, use of such a conventional gyroscope-based surveying tool requires a skilled operator to interpret the information produced by the surveying tool, manually determine an appropriate course of action upon interpreting the information, and, finally, initiating an appropriate change to the vertical drilling rig operation by use of one or more user actuated controls. It can be appreciated that these operations require the presence of a relatively highly skilled operator at the vertical drilling rig. It can be further appreciated that the human factor associated with such approaches results in a relatively slow response time to changing well conditions and reduced surveying accuracies.
During conventional horizontal and vertical drilling system operations, as discussed above, the skilled operator is relied upon to interpret data gathered by various down-hole information sensors, modify appropriate controls in view of acquired down-hole data, and cooperate with other operators typically using verbal communication in order to accomplish a given drilling task both safely and productively. In this regard, such conventional drilling systems employ an xe2x80x9copen-loopxe2x80x9d control scheme by which the communication of information concerning the status of the drill head and the conversion of such drill head status information to drilling machine control signals for effecting desired changes in drilling activities requires the presence and intervention of an operator at several points within the control loop. Such dependency on human intervention within the control loop of a drilling system generally decreases overall excavation productivity, increases the delay time to effect necessary changes in drilling system activity in response to acquired drilling machine and drill head sensor information, and increases the risk of injury to operators and the likelihood of operator error.
There exists a need in the excavation industry for an apparatus and methodology for controlling an underground boring tool and boring machine with greater responsiveness and accuracy than is currently attainable given the present state of the technology. There exists a further need for such an apparatus and methodology that may be employed in vertical and horizontal drilling applications. The present invention fulfills these and other needs.
The present invention is directed to an excavation system which employs a navigation sensor system to provide information used to control an adjustable steering mechanism provided on or in a down-hole cutting tool. According to one embodiment, the excavation system includes a cutting tool coupled to a drill pipe. An adjustable steering mechanism is provided on or in the cutting tool. A driving apparatus is coupled to the drill pipe for moving the cutting tool along an underground path. The cutting tool can be a boring tool or a reamer.
The excavation system further includes a navigation sensor system and a controller. The controller produces a control signal to adjust the steering mechanism for directing the cutting tool along the underground path in accordance with one or both of position information and orientation information produced by the navigation sensor system.
In one configuration, the navigation sensor system includes at least one gyroscope. In another configuration, the navigation sensor system includes at least one accelerometer. In a further configuration, the navigation sensor system includes at least one magnetometer.
According to one control arrangement, the controller includes a processor disposed in the cutting tool, and the processor produces the control signal to adjust the steering mechanism. In another control arrangement, the controller includes a processor provided at the driving apparatus, and this processor produces the control signal. In a further control arrangement, the controller includes a first processor disposed in the cutting tool and a second processor provided at the driving apparatus. The first or second processor produces the control signal.
In another configuration, the excavation system interacts with an above-ground tracker. A controller of the excavation system, which can be a distributed controller, is communicatively coupled to the above-ground tracker. For example, the controller can include a first processor disposed in the above-ground tracker and a second processor provided at the driving apparatus or in the cutting tool. The first or second processor can produce the control signal for adjusting the steering mechanism.
In accordance with another embodiment of the present invention, an excavation system includes a cutting tool coupled to a drill pipe, and an adjustable steering mechanism provided on or in the cutting tool. A driving apparatus is coupled to the drill pipe for moving the cutting tool along an underground path. A navigation sensor system, according to this embodiment, includes an above-ground receiver, and a transmitter and gyroscope respectively provided in the cutting tool. The navigation sensor system generates a position signal and an orientation signal. A controller produces a control signal to control the driving apparatus in response to one or both of position information and orientation information produced by the navigation sensor system.
The controller, in one control arrangement, includes a processor disposed in the cutting tool, and the processor produces the control signal to control the driving apparatus. In another control arrangement, the controller includes a processor provided at the driving apparatus, and this processor produces the control signal. In a further control arrangement, the controller includes a first processor disposed in the cutting tool and a second processor provided at the driving apparatus. The first or second processor produces the control signal.
In yet another control arrangement, the controller includes a first processor disposed in the cutting tool and a second processor provided at the above-ground receiver. The first or second processor produces the control signal. In another control arrangement, the controller includes a first processor disposed in the cutting tool, a second processor provided at the above-ground receiver, and a third processor provided at the driving apparatus. In this arrangement, the first, second or third processor produces the control signal. It is understood that two or more processors can be involved in the computations leading to transmission of the control signal by one of the two or more processors.
In accordance with a further embodiment of the present invention, an excavation system includes a cutting tool coupled to a drill pipe, an adjustable steering mechanism provided on or in the cutting tool, and a driving apparatus coupled to the drill pipe for moving the cutting tool along an underground path. The system further includes a navigation sensor system and a controller. The controller produces a control signal to adjust the driving apparatus for directing the cutting tool along the underground path in accordance with one or both of position information and orientation information produced by the navigation sensor system. The system may further include an above-ground tracking system. The system may employ a single location or multiple location control arrangement as discussed above and herein.
The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.